Feline Leukaemia Virus: a guide for cat owners

Feline Leukaemia Virus (FeLV) is widespread in South Africa and cats infected with it are predisposed to other illnesses and infections that could kill them. They’re also a danger to other cats. Here’s what you need to know to protect your cat:

What is Feline Leukaemia Virus (FeLV)?

Feline leukaemia is a virus that infects only cats. It cannot be passed on to humans or dogs or other animals. Cats worldwide are infected with the virus, but the prevalence of infection varies greatly depending on their age, health, environment, and lifestyle. Because it suppresses the immune system it can also predispose cats to deadly infections.

How is it spread?

Cats infected with FeLV serve as persistent sources of infection. The virus is shed in very high quantities in saliva and nasal secretions, but also in urine, faeces, and milk. Cat-to-cat transfer of the virus may occur from a bite wound, during mutual grooming, and (though rarely) through the shared use of litter boxes and feeding dishes. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing. Feline Leukaemia Virus doesn’t survive long outside a cat’s body—probably less than a few hours under normal household conditions.

 Which cats are at greatest risk of infection?

  • Cats that have not been immunised against the virus and that are living with infected cats or with cats of unknown infection status.
  • Kittens are much more susceptible to infection than adult cats. Although FeLV infection susceptibility decreases as cats get older, the risk does not necessarily reach zero; it depends greatly on a cat’s lifestyle and degree of viral exposure.
  • Cats with access to the outdoors and cats that have contact with cats with access to outdoors.
  • Cats that live with FeLV-infected cats.
  • Cats that may encounter other cats with unknown FeLV status.

Cats may live for years with the virus without experiencing symptoms; however their status means they are always a risk to other cats.

What does Feline Leukaemia Virus do to a cat?

The virus is the most common cause of cancer in cats, it may cause various blood disorders, and it may lead to a state of immune deficiency that hinders the cat’s ability to protect itself against other infections and diseases.

FeLV-associated diseases include lymphoma, leukaemia, anaemia and infectious diseases that occur because of the FeLV’s immunosuppressive effects.

What are the signs of disease caused by FeLV?

During the early stages of infection, it is common for cats to exhibit no signs of disease at all. However, over time — weeks, months, or even years — the cat’s health may progressively deteriorate or be characterised by recurrent illness interspersed with periods of relative health.

Symptoms can include:

  • Loss of appetite
  • Slow but progressive weight loss, followed by severe wasting late in the disease process
  • Poor coat condition
  • Enlarged lymph nodes
  • Persistent fever
  • Pale gums and other mucous membranes
  • Inflammation of the gums (gingivitis) and mouth (stomatitis)
  • Infections of the skin, urinary bladder, and upper respiratory tract
  • Persistent diarrhoea
  • Seizures, behaviour changes, and other neurological disorders
  • A variety of eye conditions
  • In unspayed female cats, abortion of kittens or other reproductive failures

 How is FeLV diagnosed?

Any new cats or kittens should be screened for FeLV infection before being introduced into a household.

Household cats that go outdoors or share a house with cats that go outdoors should be FeLV-tested at least yearly. Also, any cat that becomes clinically ill should be tested for FeLV immediately if it shares a household with an FeLV-infected cat.

In some cats it can take up to four months to figure out the stage of FeLV infection.

To test for FeLV your vet will take a blood sample. This is a relatively fast and simple process that gives immediate positive or negative results.

FeLV tests detect infection, not clinical disease. A decision for euthanasia should never be based solely on whether a cat is ‘confirmed’ FeLV-infected. Some cats may test positive for FeLV and then clear themselves of the infection. So before deciding to euthanase based on a test result, it is advisable to retest the cat in a month’s time.

Vaccinate cats against FeLV

How can I protect my cat from becoming infected?

The only sure way to protect cats is to prevent their exposure to FeLV-infected cats. Vaccination goes a long way to protect your cat from this virus. FeLV vaccination is a non-core vaccination and is not always included in your annual vaccination. Ensure that the vet does include this in your cat’s vaccinations. This also has be repeated on an annual basis to maintain their immunity against the virus. Adopt only infection-free cats into households with uninfected cats and have uninfected cats vaccinated. FeLV vaccination of infected cats is not beneficial.

Living with FeLV

Outcomes of FeLV infection depend, among other things, on an individual cat’s immune status, genetic makeup and age and the presence of any other infectious diseases. However, with proper management by the cat’s owner and healthcare from the veterinary team, cats with this retrovirus can live longer, more comfortable lives.

The best situation for an FeLV-infected cat is to live in an indoor-only environment and be the only cat in the household. In a multi-cat household, it can be difficult for the owner to confine FeLV-exposed cats, assess risk to other cats, and decide how to manage the situation. Close partnership with the veterinary team is essential in these situations.

If an owner is unwilling to separate the FeLV-infected cat from non-infected cats, then the non-infected cats should be adequately FeLV-vaccinated. Vaccination does not guarantee 100% protection, especially in high-exposure environments.

No new cats should be added to the household because this would disrupt the social structure and possibly increase the risk of cat fights and bites. Since FeLV is primarily transmitted by close contact (both friendly and aggressive) and the sharing of food bowls, water bowls and litterboxes, it’s unlikely that an owner will create an environment completely void of FeLV infection. However, providing separate feeding stations for infected and non-infected cats may help decrease the degree of exposure.

The stress of introducing a new cat to the household may also put the infected cat’s immune system under strain. They may then become ill. The new cat may also bring in parasites or bacteria or viruses which the infected cat may succumb to.

If a cat is FeLV-positive but showing no clinical signs, it should have a full physical examination at least twice a year and at every vet visit

If a cat is FeLV-positive but displaying no clinical signs, it should receive a physical examination at least twice a year and at each veterinary visit.

Infected queens and toms should not be bred, and they should be spayed or neutered, respectively, to reduce behaviours that increase risk of disease exposure or transmission, such as escaping, fighting and roaming. This also decreases the risk that the infected cats will infect other cats in the area.

FeLV-infected cats should still be vaccinated with core vaccines (rabies, feline herpesvirus, calicivirus and panleukopenia virus) and possibly vaccinated more frequently (for example, every six months) based on an individual cat’s risk assessment and lifestyle.

A nutritionally balanced diet is also essential. Ask your vet for advice. Raw diets should be avoided in FeLV-infected cats because of the increased risk of foodborne bacterial and parasitic diseases.

FeLV remains infectious for only minutes in the environment and is readily inactivated with soap and disinfectants, so frequent cleaning of litterboxes and food bowls may decrease viral load. Please ask your veterinarian for a recommendation for a disinfection.

FeLV cannot be transmitted to humans.

 Managing clinically ill FeLV-positive cats

Early veterinary intervention is key to a successful treatment outcome in FeLV-infected cats that display clinical signs. Most FeLV-infected cats respond well to appropriate medications and treatment strategies, but they may require a longer or more aggressive course of treatment and need to be more closely monitored during recovery. To date, no treatment has been shown to reverse or cure FeLV infection in cats.

Unfortunately many FeLV cats will succumb to complications related to FeLV infection. It is important to discuss your cat’s quality of life with your veterinarian and have a treatment and euthanasia plan in place. This will ensure your cat will maintain the best quality of life possible.